Reversible rack and pawl jack



Patented Oct. 5, 1948 UNITED STATES PATENT OFFICE REVER'siBLE R cnnNi) PAWL more Achille Kais, Detroit, Mich. Application July 13, 1944, Serial so. 5443;77

This invention relates to llfting'ja'ck construction, the primary object of the invention being to provide a quick acting heavy duty jack of exceptionally light construction.

Another object of the invention is to provide a rack bar and movable housing operating over the rack bar, the movable housing constituting the lifting element of the jack.

Still another object of the, invention is to provide a jack including a's'liding pawl and a pivoted pawl, the pawls being: actuated. by a jack lever to raise or lower the jack as the jack lever is'moved vertically.

A further object of the invention is to provide a pair of pawls mounted on 'the movable member of the jack, in such a way that when the jack is being operated, one pawl will act to hold the movable part of the jack against downward movement'under the weight of the load being lifted. when the other pawl is being moVed' to-a position to elevate the movable section of th jack.

With the foregoing and other objects in view which will appear as the description proceeds,

the invention consists of certain novel details of of the jack.

Referring to the drawing in detail, the base or supporting plate of the jack is indicated by the reference character '5, the plate being provided with enlargements 6 pressed therefrom, reenforcing the supporting plate, and at the same time providing a supporting surface which will permit the jack to be readily slid into position under a motor vehicle bumper, in lifting the vehicle.

Rising from the base or supporting plate 5, is a rack bar constructed of a length of heavy sheet metal material and formed to provide a hollow structure. An angle bar 8, of a length equal to the length of the rack bar, is positioned within the rack bar, said angle bar being welded to the rack bar, bracing the rack bar for strength.

The reference character 9 indictaes the jack 1 claim. (01. 2-54-4111) housing is constructed to move vertically over'the' This jack housing is constructed.

housing which'not only houses the pawls used'ih operating the jack, but at the same time con stitutes the lifting element of the jack, since the rack bar I;

preferablyofsheet metal material and so shaped that it conforms to the shape of the rack barl, as is clearly shown by Fig. 2 of the drawing.

The sections of the housing are held togetherv by meansv of the rivets [0 which structure pro= vides'a space for the rocking head ll, whioh is shown as pivotally mounted within the housing, on the pin l2 which extends through the side walls of the housing.

This rocking head l-l embodies plates [3 which are held in spaced relation with respect to each other, by means of the spacer studs 14, which studs also provide means to receive one end of the operating lever l5, which. is formed with "a slotted end to fit over the studs, as shown by Fig. 1.

The reference character I6 indicates a pawlwhich is formed with an elongated opening to receive the pin l2, so that the pawl l6 may slide horizontally, towards and away from the rack bar. The pawl I6 is formed with a rack bar engaging tooth l'! and a tooth l8 which is also adapted to engage the rack bar, when the rocking head is swung upwardly, during the lifting operation.

A tail-piece indicated at I8 is formed on the pawl l6, and is disposed between the pins 19 and 20 which connect the plates of the rocking head. Pins 2i and 22 also connect the guide members of the rocking head II, the pin 2| being so arranged that it will contact with the pawl 23 pivoting the pawl to disengage the pawl and rack bar.

Positioned within the rocking head H, is a spring member 24 which is looped around the pins 20 and 22, one end of the spring member 24 engaging thepawl 23 to normally hold the pawl into engagement with the teeth of the rack bar, while the opposite end of the spring member engages the end of the tail-piece l8, normally urging the pawl l6 inwardly so that the tooth l1 thereof engages the teeth of the rack bar.

The lifting shoulder of the jack is indicated by the reference character 25, and embodies a plate which isbent-upon itself, and formed with openings to accommodate the rivet I0 for securing the lifting shoulder in position on the jack housing- As shown the upper edge of the lifting shoulder is recessed so that the jack will readily fit under a bumper, axle or the like to be lifted,

in such a way that the jack will not slip with the movement of the housing.

A shouldered spacing stud 26 is held between the plates of the housing 9 to hold the plates in proper spaced relation with respect to each other under severe lifting strain which may be directed to the jack.

In the operation of the jack to lift a load, the lever I is moved downwardly to a position where the jack may be moved with the lever, whereupon the jack is positioned under a motor vehicle wheel bumper or axle to be elevated with the lifting shoulder contacting the axle or bumper. The lever I5 is now moved downwardly with the result that the pawl 23 acting as the pivot point for the housing, causes the housing and load supported by the housing to move upwardly a predetermined distance. With the upward movement of the housing over the rack bar 8, the tooth I! of the pawl it moving therewith, is moved to engage the teeth of the rack bar I, the tooth l1 coming to rest on one of the teeth of the rack bar temporarily supporting the weight. This movement of pawl 16 is accomplished by the action of the upper end of the spring 24 which acts to urge the pawl towards the rack bar. upward movementof the housing to lift an article is thus described, and it is to be understood that by continual vertical reciprocation of the lever, thehousing will be moved upwardly with a step by step motion to lift the object supported thereby.

When lowering the housing and load, the lever 15 is swung upwardly to the limit of its upward movement with the result that the weight of the load is temporarily supported by the tooth N3 of the pawl 16, the pawl 23 being free to swing outwardly past the end of the tooth with which it is engaged, and out of contact with the rack bar. As the lever I5 is lowered, the pawl 23 moves downwardly until the downward pivotal move- One step in the mounted on the head and having an elongated ment of the pawl 23 causes the pawl to engage a lower tooth of the bar, supporting the weight of the load while the lever and rocking head are again swung upwardly repeating the lowering operation. It will, of course, be understood that the vertical reciprocation of the lever is repeated in this manner, until the load is lowered to the desired position.

What is claimed is:

A lifting jack comprising a rack bar, a housing mounted for movement longitudinally of the rack bar, an operating head pivotally mounted within the housing, a, pivot pin on which the operating head is mounted, said pivot pin being disposed eccentrically of the rocking head, a sliding pawl REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,445,430 Dardani Feb. 13, 1923 1,483,603 Bibb Feb. 12, 1924 1,520,937 Dickey Dec. 30, 1924 1,571,132 Marchesseault Jan. 26, 1926 2,249,050

Schmidt July 15, 1941 

